Locking device

ABSTRACT

In the disclosed locking plug arrangement, a locking plug consists of a cylindrical body molded from synthetic material and having an integral peripheral sealing lip and one or more integral laterally projecting catches and a cast housing with a bore to receive the plug body in sealing relation and with a transverse passage to receive a projecting catch.

BACKGROUND OF THE INVENTION

This invention relates to a locking plug arrangement using a plug whichmay be releasably locked in a bore.

In fluid control technology, plugs are used which are shaped to providean abutment for a control piston movable in a bore, and which also sealthe bore against escape of hydraulic fluid. Conventional plugs of thistype may be positively locked with respect to a housing containing thebore, even under high dynamic loads, by devices such as bolts, pins orlocking rings. A disadvantage of this type of locking plug, however, isthe large number of structural details required as well as the high costof manufacturing and assembly, especially in connection witharrangements for removing the plug.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide alocking plug arrangement using a releasable locking plug which overcomesthe disadvantages of the prior art.

Another object of the invention is to provide a locking plug which canbe easily installed and removed, but is positively fixed in positioneven under high dynamic loads.

These and other objects of the invention are attained by providing alocking plug having a body with an outer surface adapted to be receivedin sealing relation in a bore and having a catch member projecting fromthe body which is arranged to be received in a passage extendingtransversely to the axis of the bore. A locking plug arrangementaccording to the invention may be mass produced by making the plug froman injectable synthetic material and making a die-cast housing toreceive the plug. In this way, all of the necessary elements of thelocking arrangement may be provided during the formation of the plug andthe housing so that no machining will be required. By making the plug inthe form of a hollow cylinder, the amount of material required can bereduced, providing economic advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects and advantages of the invention will be apparent from areading of the following description in conjunction with theaccompanying drawings in which:

FIG. 1 is a longitudinal sectional view illustrating a representativeembodiment of the invention in which a locking plug is received andlocked in a housing bore;

FIG. 2 is a sectional view of the locking plug arrangement shown in FIG.1, taken along line II--II and looking in the direction of the arrows;

FIG. 3 is a longitudinal sectional view of a second representativeembodiment of the invention showing a locking plug received and lockedin a housing bore; and

FIG. 4 is a sectional view of the embodiment shown in FIG. 3, takenalong the line IV--IV and looking in the direction of the arrows.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the typical embodiment shown in FIGS. 1 and 2, a locking plug 1, inthe shape of a hollow cylinder, has a closed end 1.1 and a cylindricalouter wall 1.2 which is in contact with a wall of a bore 2 in a housing3. The housing 3 may, for example, be part of a valve box for a fluidcontrol system, and may be formed as a die casting. A passage 4 isformed in the housing 3 substantially perpendicular to the centerline ofthe bore 2 and a catch member 5, projecting outwardly from thecylindrical outer wall 1.2 of the locking plug 1 and capable of beingbent resiliently toward the cylindrical outer wall 1.2, is received inthe passage 4. In addition, the plug 1 has a sealing lip 6 engaging thebore 2 and an annular shoulder 7, which may, for example, be an abutmentfor a control system movable in the bore 2 (not shown). Also cast intothe housing 3 are a longitudinal groove 8 extending along the bore 2 asfar as the passage opening 4, and two abutment surfaces 9.1 and 9.2 inthe opening 4. In the locked condition of the plug, an abutment surface10 at the end of the catch member 5 engages the surface 9.1 essentiallyin area contact therewith and hence is not subject to wear.

Two lateral surfaces 11 and 12 of the catch member 5, visible in thecross-sectional view of FIG. 2, are confined by two side walls 13 and 14of the passage opening 4 to restrain the plug 1 against rotation in thelocked condition. The clearance between the lateral surfaces 11 and 12and the side walls 13 and 14 is selected so that the catch member 5 canmove into the passage opening 4 without difficulty.

The embodiment illustrated in FIGS. 1 and 2 is especially easy toassemble. The plug 1 is first placed in the open end of the bore 2 sothat the catch member 5 is aligned with the longitudinal groove 8. Thenthe plug 1 is pushed into the bore 2 in the direction of the arrow sothat the catch member 5 is resiliently bent toward the cylindrical outerwall 1.2 of the plug until the abutment surface 10 of the member 5 hasbeen moved past the surface 9.1 of the passage 4. This insertion motionin the direction of the arrow A is terminated by contact of the catchmember 5 with the edge of the abutment surface 9.2 at the bore 2. Atthat point, the catch member 5 will spring outwardly to the positionshown in FIG. 1 and will lodge in the passage 4. The plug 1 is thenpositively fixed both axially and angularly in the bore 2 by the catchmember 5. It should be emphasized that the insertion of the locking plug1 in the bore 2 can be accomplished by hand without requiring anyspecial tools. Moreover, the assembly operation may also be automatedwith very low equipment cost.

Furthermore, the plug 1 can be removed from the bore 2 withoutdifficulty. For that purpose, a mandrel- or rod-like tool (not shown)may be inserted in the passage 4 to push the catch member 5 toward thecylindrical outer wall 1.2 far enough so that it can enter thelongitudinal groove 8. In this way, the plug 1 is released from itslocked position in the bore 2. By inserting the mandrel- or rod-liketool at an upward angle, axial motion of the plug will be produced inthe direction opposite to the arrow A as the catch member 5 isdepressed. This facilitates release and removal of the plug 1 from thebore 2. In an especially advantageous embodiment, the sides of thelongitudinal groove 8 are flush with the side walls 13 and 14 of thepassage 4 so that the catch member 5 need be depressed only as far asthe base of the lengthwise groove 8 in order to release the plug 1.

Further ease of assembly is provided by the presence of the sealing lip6 which, by itself, forms the seal between the plug 1 and the bore 2.Consequently, the cylindrical outer wall 1.2 may be dimensioned toprovide a loose fit with respect to the diameter of the bore 2, therebygreatly reducing friction between plug 1 and housing 3 both uponinsertion and upon removal of the plug 1. To enhance the sealing effectof the plug 1, an O-ring may be inserted between the annular shoulder 7and the sealing lip 6 to bias the sealing lip 6 against the wall of thebore 2.

In the embodiment shown in FIGS. 3 and 4, a plug 1' is inserted in abore 2' of a housing 3'. Two opposed passages 4' and 4" are cast in thehousing 3' and two catch members 5' and 5", formed as lugs on the plug1' are received in those passages. Each of the catch members 5' and 5"is provided with a lower inclined surface 15.1 and 15.2, respectively,and an upper inclined surface 16.1 and 16.2, respectively. The lowerinclined surfaces 15.1 and 15.2 should preferably form an angle of about55°-65° with the axis 17 of the plug 1' and the upper inclined surfaces16.1 and 16.2 should preferably have an angle of about 87°-89° with theaxis 17, which has been exaggerated in the drawing for the sake ofclarity The plug 1', similar to plug 1, has a peripheral sealing lip 6in sealing engagement with the bore 2' and an annular shoulder 7. Inaddition, the plug 1' is formed with a polygonal aperture 18 in an innershell 19 into which a correspondingly shaped assembly tool may beinserted to rotate the plug 1'. For economy of material, a series ofrecesses 21.1-21.6, separated by webs 22.1-22.6, is formed at one end ofthe plug between the inner shell 19 and an outer shell 20, only tworecesses 21.1 and 21.4 and two webs 22.1 and 22.4 being visible in thesectional view of FIG. 3. At the other end of the plug, an annulargroove 23 with a continuous base 24 which may, for example, receive aspring (not shown) is formed between the inner shell 19 and the outershell 20. Especially important to the operation of this locking deviceare two longitudinal grooves 8' and 8" formed along the bore 2' in thehousing 3' (only one being visible in FIG. 3) which extend to the levelof the bottom edge of the passages 4' and 4".

For better understanding of the operation of this embodiment, FIG. 4additionally shows two partial annular grooves 25 and 26 through whichthe catch members 5' and 5" of the plug 1' may be rotated out of thelongitudinal grooves 8' and 8" to the passages 4' and 4" after the plug1' has been moved far enough into the bore 2'. With the aid of a simpletool inserted in the aperture 18, the plug 1' can thus be installed by apushing and turning motion, and may be removed by a turning and pullingmotion. Since the plug is locked in the bore in this manner, the catchmembers 5' and 5" need not be resilient and may be substantially rigid.

If desired, an embodiment of the type shown in FIGS. 3 and 4 could bearranged with a locking plug having only one catch member or more thantwo catch members. The provision of upper inclined surfaces 16.1 on theholding members 5' and 5" has the advantage that, when the plug 1' islocked and is forced in the direction opposite to the direction of thearrow A, the inclined surfaces engage the upper wall of the passages 4'and 4". Thus, after the motion to the locking position has beencompleted, those surfaces of the catch members 5' and 5" may be pressedagainst the upper walls of the passages 4' and 4", so that the stressapplied by the plug is distributed over a greater area. This isespecially favorable in prolonging the service life of the plug.

Because the plug is shaped substantially as a hollow cylinder, aconsiderable saving of material is realized in the mass production ofplugs according to the invention. Furthermore, the wall thicknesses ofthe plugs 1 and 1' are dimensioned so that optimal flow conditions areachieved when the plugs are injection molded from synthetic material.Manufacture of the locking arrangement comprising the injection moldedlocking plug and the die cast housing requires no machining or othercostly operations. Economic advantages result not only from simplifiedassembly but also from savings of material and reduced cost ofproduction, especially for the embodiments shown in the drawings.

Although the invention has been described herein with reference tospecific embodiments, many modifications and variations therein willreadily occur to those skilled in the art. Accordingly, all suchvariations and modifications are included within the intended scope ofthe invention.

I claim:
 1. A sealing plug to be inserted into and locked in a bore of ahousing having a passage extending transverse to the bore and locatedinwardly from an open end of the bore comprising a plug body havingcatch means projecting from the plug body to be received in thetransverse passage and having a peripheral sealing surface locatedinwardly from the catch means in the direction of plug insertion forsealing engagement with the bore at a location inwardly in the bore fromthe transverse passage, the sealing surface further including means forbiasing the sealing surface to engage the bore surface.
 2. A sealingplug according to claim 1 wherein the plug body is in the form of ahollow cylinder with a closed end and has an encircling sealing lipadjacent to the closed end of the hollow cylinder.
 3. A sealing plugaccording to claim 1 wherein the plug body is substantially a hollowcylinder closed at one end.
 4. A sealing plug according to claim 1wherein the plug sealing surface is integral with the plug body.
 5. Asealing plug according to claim 1 wherein the plug is made from aninjection-moldable synthetic material.
 6. A sealing plug according toclaim 1 wherein the catch means is an integral part of the plug body andis arranged to lock the plug in both angular and longitudinal directionsin the bore.
 7. A sealing plug according to claim 1 wherein the catchmeans is resilient.
 8. A sealing plug according to claim 7 wherein theplug body has a cylindrical outer wall and wherein the catch meansincludes a catch member normally projecting outwardly at an angle fromthe cylindrical outer wall of the plug body and the resilience of thecatch means permits motion of the member from its normal position towardthe cylindrical outer wall.
 9. A locking arrangement comprising asealing plug to be inserted into and locked in a bore of a housinghaving a passage extending transverse to the bore and located inwardlyfrom an open end of the bore including a plug body having catch meansprojecting from the plug body to be received in the transverse passageand having a peripheral sealing surface located inwardly from the catchmeans in the direction of plug insertion for fluid-sealing engagementwith the bore at a location inwardly in the bore from the transversepassage, and a cast housing having a bore and a transverse passage castinto the housing to receive the locking plug body and the catch means,respectively.
 10. A locking arrangement according to claim 9 wherein thecross-sectional configuration of the transverse passage adjacent to thebore is arranged to receive the catch means with a predeterminedclearance in the angular direction.
 11. A locking arrangement accordingto claim 10 wherein the plug body has a cylindrical outer wall andwherein the catch means includes a catch member normally projectingoutwardly at an angle from the cylindrical outer wall of the plug bodyand is resilient to permit motion from its normal position toward thecylindrical outer wall and wherein the free end of the catch member hasa surface area which engages a wall of the transverse passage to retainthe plug body in axially fixed position in the bore.
 12. A lockingarrangement according to claim 9 wherein catch means is resilient andwherein the housing bore includes a cast longitudinal groove extendingfrom one end of the bore at least to the transverse passage so that,when the plug is pressed into the bore, the catch means is received inand guided by the groove until it reaches the transverse passage whereit is resiliently moved into the passage.
 13. A sealing plug accordingto claim 1 wherein the plug body has a closed end and includes anannular projection at the end inserted into the bore.
 14. A sealing plugaccording to claim 1 wherein the plug body has a cylindrical outer walland wherein the catch means comprises a substantially rigid catch memberprojecting outwardly from the cylindrical outer wall of the plug.
 15. Asealing plug according to claim 14 wherein the forward and rear sides ofthe catch member with respect to the direction of the motion of pluginsertion extend from the plug body at an angle toward the rear of theplug body.
 16. A sealing plug according to claim 14 wherein the plugbody has a polygonal aperture acessible from the rear end of the plugwith respect to the direction of motion of plug insertion.
 17. A sealingplug according to claim 16, wherein the plug body includes an innershell and an outer shell connected by ribs and wherein the polygonalaperture is in the inner shell of the plug body.
 18. A sealingarrangement including a locking plug according to claim 14 and a casthousing having a bore and a transverse passage cast into the housing andhaving a cast longitudinal groove extending along the bore from one endat least to the region of the transverse passage to guide the catchmeans, the groove being angularly offset from the location of thepassage and connected thereto by at least a segment of a cast-in annulargroove.